Chickenpox is one of the most common infectious diseases in children. It occurs more frequently in winter and spring than at other times of the year. Also known as varicella, chickenpox is caused by a herpesvirus and is characterized by a very itchy red rash on the skin. The red rashes usually start on the chest, back, or face, and can spread out quickly over the entire body. This may make you feel terrible. In most cases, chickenpox is a mild disease that resolves by itself within a few weeks. Rarely, the disease can trigger significant complications, including skin infection and lung inflammation. If you are parents or if you have never had chickenpox, it is necessary to pay attention to this common viral illness, especially in winter and spring.

What causes chickenpox?

Chickenpox is caused by varicella-zoster virus (VZV), also known as human herpesvirus type 3 (HHV-3), which is a DNA virus. VZV is one of the eight herpesviruses known to infect humans. The other seven are Herpes Simplex Virus-1 (HSV-1) , Herpes Simplex Virus-2 (HSV-2), Epstein-Barr virus (EBV/HHV-4), Cytomegalovirus (CMV/HHV-5), Human Herpesvirus type 6 (HBLV/HHV-6), Human Herpesvirus type 7 (HHV-7), and Human Herpesvirus type 8 (KSHV/HHV-8). VZV is considered an exclusively human virus because the virus generally only affects humans. But some primates such as gorillas and chimpanzees can also be affected. VZV can survive in external environments for hours, or even for as long as two days.

How can you get infected?

Chickenpox can be easily spread from person to person. According to estimates, 90% of all chickenpox cases are occurring in children younger than 10. The transmission ways of chickenpox are similar to that of the flu. An individual can get chickenpox via directly touching the blisters, saliva or mucus of an infected person, via inhaling the air when an infected person is coughing or sneezing, or via touching contaminated items. An infected person can spread the disease to others even before the typical rash appears. Each year, chickenpox outbreaks continue to occur in some regions of the world. Schools are the most common place that children get chickenpox. Although chickenpox is largely a childhood disease, it can also affect adults. Adult people who have never had the disease are recommended to be cautious of it, especially during the periods of chickenpox outbreaks.

Can chickenpox cause serious health problems?

Primary infection with VZV usually causes chickenpox. The illness is fairly mild and typical symptoms include fever, abdominal pain, rash, tiredness, poor appetite, and coughing. These symptoms start 10-21 days after exposure to the virus. In most healthy children, chickenpox is a self-limited infection. The symptoms last for a few days and then go away; a complete recovery is common. However, in susceptible groups such as infants, pregnant women, and those with weakened immune systems due to infections, diseases or drug treatments, the incidence of hospitalization and mortality of chickenpox is significant. Severe complications of chickenpox may include skin infection, lung inflammation, brain inflammation, bleeding problems, sepsis, and dehydration, which may even cause death.

What does recurrent infection with VZV cause?

Some viruses can remain dormant in the body for a long period of time after initial infection, and reactivate to cause health problems later in the infected person. VZV is one of such viruses. As mentioned above, primary infection with VZV causes chickenpox, which is mild and rarely causes complications. VZV enters through the respiratory system, spreads throughout the body and causes various symptoms. Once the illness chickenpox resolves, the virus remains dormant in the nervous system, including the cranial nerve ganglia, dorsal root ganglia, and autonomic ganglia. Later in life, VZV can reactivate to cause shingles (herpes zoster), a painful, maculopapular rash usually on one side of the body. It’s estimated that 10-20% people infected with VZV will develop shingles later in life. In summary, primary VZV infection causes chickenpox, which is usually seen in children, teens, and young adults, whereas reactivation of VZV causes shingles, which is more often seen in older adults but rarely seen in children.

How to protect against chickenpox?

The first chickenpox vaccine was introduced in the 1970s. Currently, chickenpox vaccines are recommended in many countries. Thanks to chickenpox vaccines, the incidence of the once extremely widespread disease has been significantly reduced. Getting vaccinated is the best way to protect you from getting the disease. One dose of the chickenpox vaccine prevents 95% of moderate disease and 100% of severe disease, and two doses are even more effective. The chickenpox vaccine contains a small amount of attenuated live VZV. An attenuated virus can stimulate an immune response and create immunity without causing illness. Occasionally, vaccinated people get chickenpox, but they usually recover faster than those who have not been vaccinated. The chickenpox vaccine has been reported to have certain side effects such as redness, stiffness, and soreness at the injection site. But these side effects are generally mild. If you are not sure whether you should get vaccinated, go to your doctor for help.

Recent research on chickenpox

The aim of current chickenpox treatment is to ease symptoms. Children and adult patients may be treated differently. Antiviral drugs can be used to deal with the most severe cases and shorten the duration of the infection. To develop more effective treatments for chickenpox, scientists have been studying the molecular pathogenesis of VZV. A recent study has shown that a VZV protein called glycoprotein C helps the virus spreads in the body, suggesting that this protein plays a role in VZV associated pathology.

In summary, chickenpox is a viral illness that is usually mild. But the illness may cause severe problems in some cases. Susceptible groups such as infants, pregnant women, and people with weakened immune systems are more likely to have severe complications of chickenpox. The good news is that there are vaccines to prevent the illness. You can consult your doctor about whether you should get vaccinated. Chickenpox occurs more frequently in winter and spring. So, pay more attention to the illness in these seasons.